I've never had this happen to me before

I'm uploading a video to youtube that simply shows you the problem, but it's taking forever for some reason, so I'll edit this later with a link and just attempt to describe the problem now.

Basically, there's a small section of my map that doesn't show up in game when you are standing in certain spots. When you stand in one area, it appears as if it has the nodraw texture, allowing you to see through it to the skybox, but if you move a little, it suddenly appears. This is obviously not what it should be doing, and I can't seem to fix it.
I've tried using the compile log checker, but it doesn't find any errors.

Well i decided to just delete the ramp and start over. The first time I made it, i got lazy and just moved all the vertices's so it was at an angle, and that probably messed it up. The second time, i broke out my awesome geometry skills to figure out what angle to turn the ramp by using ctrl+m and rotating the z axis, which fixed the problem.

That fixed the problems with the disappearing brushes, and now I'm looking into optimizing what i have, then the rest of the map as I go., which probably wont fun. I appreciate the help.